Baker: Muscle Contraction and Regulation Flashcards
(60 cards)
Levels of organization within a skeletal muscle
myofilaments myosin thick filaments and actin thin filaments myofibril muscle fiber muscle fibers muscle
There are many myosin (blank) and all have similar (blank) domains. They have differences in the (blank) that correspond to differences in cargo and regulation.
types; motor; tail
Which type of myosin is involved in cell division?
Myosin IIa
Which type of myosin is involved in melanosome transport and certain neurological functions?
Myosin V
What is the disease caused by a point mutation in myosin Va which leads to hypopigmentations and neurological defects?
Griscelli’s Syndrome
Which type of myosin is involved in maintaining organization of actin-filled stereocilia?
Myosin VI and Myosin VII
What are mutations in myosin VI and VII associated with? What are certain myosin VII mutations associated with?
hearing loss; Usher syndrome
Muscle myosin II is a (blank). Each heavy chain has what two components?
dimer; motor domain and a tail
All myosins are (blank)-based motors, and all but myosin VI are (blank)-end directed.
actin; plus
Sources for ATP in the muscle?
- ATP
- creatine phosphate
- anaerobic glycolysis
- aerobic glycolysis
- lipolysis
Under anaerobic conditions, what builds up from pyruvic acid? Does the Krebs cycle and ox phos occur?
lactic acid; no
When oxygen is present, the (blank) pathway will proceed. What are the end products?
aerobic; CO2, water, 36 ATP
At the start of muscle contraction, a myosin head lacking a bound nucleotide is locked tightly onto an actin filament in a (blank) confirmation. In an actively contracting muscle, this state is short-lived, because it is terminated when ATP binds. This is the (blank) state.
rigor; attached
In the (blank) state, a molecule of ATP binds to the back of the myosin head, this causes a change in conformation of the domains that make up the actin binding site. This reduces the affinity of the head for (blank) and allows it to move along the filament.
released; actin
In the (blank) state, the cleft closes like a clam shell around the ATP and causes the head to be displaced from the actin filament. ATP is hydrolyzed, but ADP and Pi remain tightly bound to the protein.
cocked
In the (blank) state, a weak binding of the myosin head to a new site on the actin filament causes release of Pi. This occurs with a tight binding of the head to actin.
force-generating
What is this: the force-generating change in shape during which the head regains its original confirmation. During this time, the head loses its bound ADP, and returns to the start of a new cycle.
power-stroke
At the end of a cycle of muscle contraction, the myosin head is again locked tightly to (blank) in a rigor configuration. *Note that the head has moved to a new position on the actin filament.
the actin filament
Myosin V has a much (blank) lever arm than Myosin II, so it can move across the actin filament in less cycles.
larger
Myosin V is a (blank) dute ratio motor. What is Myosin V’s duty ratio? What does Myosin V do?
high; >50% (one head of the myosin molecule must be bound to the actin filament for about 50% of the ATPase cycle); myosin V transports vesicles in cells
Myosin II is a (blank) duty ratio motor. What is Myosin II’s duty ratio?
low; 10% (one head of the myosin molecule is only bound for about 10% of the ATPase cycle)
How many heads does myosin II have? How many heads does myosin V have?
20 heads; 2 heads
myosin V is an (blank) motor, while myosin II drives (blank)
organelle; muscle contraction
It takes (blank) myosin II molecules to propel an actin filament
many
